The invention relates to a drive system for adjusting parts of motor vehicle equipment, in particular parts of a vehicle seat, as generically defined by the preamble to the main claim.
Drive systems are already known which enable adjusting various equipment parts of a motor vehicle with only one motor, but these equipment parts cannot be moved independently of one another.
From German Patent Disclosure DE 43 14 248, for instance, a drive system is known with which selective adjustment of motor vehicle equipment parts is possible. This drive system includes an electric drive motor, which has coupling means that can be displaced in the direction of the motor armature pivot axis and that cooperate with respective counterpart coupling means operatively connected to equipment parts. The disadvantage of this drive system is that the parts to be moved cannot be moved independently of one another, because only one or the other coupling can ever be actuated selectively.
From International Patent Disclosure PCT/US 97/07718, a system for seat adjustment is known that because of the combination of electromechanical adjustment and pneumatic adjustment likewise requires only one universal motor. In this apparatus, the motor selectively communicates with a relatively loud pump of the pneumatic adjusting device for filling air bags, or with a mechanical adjusting device. If the adjustment takes a long time, it can happen that the air bags will empty just as the motor is acting on the mechanical adjusting device. Thus once again, complete independence of the various power takeoff elements is not guaranteed.
The drive system according to the invention for adjusting parts of motor vehicle equipment, having the characteristics of the main claim not only has the advantage that various power takeoff elements can be driven by a single electric drive motor, but also the decisive further advantage that the various power takeoff elements of the power takeoff unit are independent of one another.
In the drive system of the invention, the necessity of using one drive motor per power takeoff element is eliminated. Considerable weight and cost advantages can thus be attained. Furthermore, the drive system can be very compact in structure, which is a further advantage.
By the provisions recited in the dependent claims, advantageous refinements of the systems defined by the main claim are possible.
For instance, it is advantageous if the at least two couplings each have one coupling actuator for actuating the couplings. These coupling actuators are triggerable individually and independently of one another, and thus the force transmission from the electric drive motor to the various power takeoff elements can be done purposefully and independently of one another via the respective couplings.
For example, these coupling actuators can be axial lifting motors, which are equipped with an axially displaceable spindle and are operatively each connected to a first coupling element of the at least two couplings.
An especially compact embodiment of the drive system of the invention is attained if the at least two couplings are disposed on the respective two ends of the at least one auxiliary shaft. This adjacent disposition of the coupling actuators makes a symmetrical, space-saving, and extremely practical design of the drive system possible.
An especially advantageous embodiment of the couplings is attained if the couplings each comprise one first coupling element and one second coupling element. What is important is that the first coupling element, which can be put into operative connection to the coupling actuator, is connected to the auxiliary shaft in a manner fixed against relative rotation, while the second coupling element, which is connected to the power takeoff unit, is rotatably connected to the auxiliary shaft only in this way is targeted influence on the force transmission possible. The two coupling elements are embodied such that in the engaged state, a frictional engagement, and in the disengaged state if at all possible no connection, exists between the touching surfaces of the two elements.
If the coupling actuators disposed adjacent the first coupling elements are to be operatively connected to the respective first coupling element, then the force of the electric drive motor can be distributed in a targeted way to the various power takeoff elements independently of one another.
In an advantageous variant, the at least two power takeoff elements of the power takeoff unit include power takeoff worm wheels connected to power takeoff shafts, whose sets of teeth each mesh with one set of worm teeth, for instance, of the respective second coupling elements.
The use of worm gears furthermore makes a self-locking design possible, which prevents undesired adjustment of the equipment parts to be adjusted. Hence complicated provisions for fixing the parts to be moved are not required.
A major advantage is obtained if the power takeoff worm wheels have different diameters, or if power takeoff worm wheels with different diameters can be used. Then the possibility exists of varying the gear ratios and of adapting the torques, applied to the power takeoff worm wheels, optimally to the applicable demands made of the parts to be adjusted.
For example, the fact that when a vehicle seat is adjusted, for instance, the seat back adjustment requires less expenditure of force than adjusting the vehicle seat height or its longitudinal position, can be taken into account appropriately.
If the drive motor is disposed centrally, for instance precisely between the at least two couplings, then an especially compact structure of the drive system is possible, and the stresses occurring in operation are optimally distributed to the drive system.
By means of a control unit connected to the drive system, the advantageous possibility exists of controlled, targeted triggering of the individual power takeoff elements of the drive system.